Hydraulic control for truck lifting mechanism



' Dec. 11, 1962 G. F. QUAYLE 3,067,887

HYDRAULIC CONTROL FOR TRUCK LIFTING MECHANISM Filed March 24, 1958 4 Sheets-Sheet l [icy l.

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ATrOP YE'Y G. F. QUAYLE Dec. 11, 1962 HYDRAULIC CONTROL FOR TRUCK LIFTING MECHANISM Filed March 24, 1958 4 Sheets-Sheet 2 INVENTOR. 6604 65 I? Qua r45 rray/vs) G. F. QUAYLE Dec. 11, 1962 HYDRAULIC CONTROL FOR TRUCK LIFTING MECHANISM Filed March 24, 1958 4 Sheets-Sheet 3 INVENTOR. .Geoeas ff Qunyu:

AWOf/VE) HYDRAULIC CONTROL FOR TRUCK LIFTING MECHANISM Filed March 24, 1958 Dec. 11, 1962 I e. F. QUAYLE 4 Sheets-Sheet 4 INVENTOR. Gecwsc f. Qun v45 United Stats 3,067,887 HYDRAULIC CONTROL FOR TRUCK LIFTIPJG MECHANISM George F. Quayle, Philadelphia, Pa, assignor to The Yale and Towne Manufacturing Company, Stamford, CDKIEL,

a corporation of Connecticut Filed Mar. 24, 1953, Ser. No. 723,36il Claims. (Cl. 214l31) This invention relates to an industrial truck, and, more particularly, to an industrial truck of the type in which a load lifting or manipulating mechanism is moved through the operation of two or more actuating means, and particularly, hydraulic rams.

My invention resides basically in the concept of means for controlling the operation of two or more hydraulic rams so that those rams will lift or manipulate a load in predetermined relation to one another. Thus, the rams will be so controlled that they may be actuated sequentially or simultaneously in such manner that the load will be moved in a predetermined path.

My invention is particularly related to a type of load lifting mechanism in which the load is moved through levers from a relatively low position to a relatively high position, the movement being contributed by two rams receiving fluid pressure preferably from a single source. Under the concept of my invention, the fluid is so directed to the rams that the levers will be actuated to move the load in a predetermined, fixed path, it being appreciated that while my invention is basically devoted to this particular type of operation, it is possible through the utilization of the concept of my invention, to manipulate the load in various other ways, as may become desirable.

As a feature of my invention, the rams are controlled through valve means that are, in turn, automatically actuated or controlled by means movable incidentally to the movement of the load. Thus, should the load be moved other than in a predetermined path, valve means will be actuated to eifect the movement of the load in the predetermined path through the control of the fluid moving to the rams. As an example, should one ram have moved more than a predetermined distance as may be required, the fluid flow to this ram will be restricted or stopped while the fluid flow to the other ram will be continued to actuate that ram to restore the proper balance of movement between the rams required to move the load in a predetermined path and in a predetermined manner. More particularly, I provide a lifting mechanism actuated by each of the rams, these lifting mechanisms being related for coordinated movement when the rams operate at coordinated speeds. As a further part of my contribution, I also provide valve means through which fluid under pressure flows to the rams, and control means for controlling the valve means so as to determine the flow of fluid to each of the rams in order to elfect the coordinated movement of the lifting mechanisms.

As a most important part of my present concept, I provide means whereby the valve control means are automatically actuated by the relative movement of the lifting mechanisms.

As a further feature of my invention, the load will be moved in either of opposed directions as determined by manual control means, with the path of movement determined by means forming part of my invention under the broad concept I have here set forth. In this connection, I utilize manual control means for superseding or over-riding the automatic control means to determine the flow of fluid relatively to each of the rams.

I have thus outlined rather broadly the more important features of my invention in order that the detailed decription thereof that follows may be better understood, and in order that my contribution to the art may be better 35188? Patented Dec. 11, 1952 appreciated. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception on which my disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of my invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of my invention, in order to prevent the appropriation of my invention by those skilled in the art.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing forming a part of the specification.

In the drawing:

FIG. 1 is a side view of a lift truck of the leverage type utilizing a hydraulic control system in accordance with my present invention;

FIG. 2 is a top plan view of the apparatus illustrated in FIG. 1;

FIG. 3 is an elevational view of part of the truck of FIGS. 1 and 2 illustrating a portion of my control system schematically;

FIG. 4 is a fragmentary side elevational view showing the leverage system of FIGS. 1 and 2 in elevated position;

FIG. 5 is a view similar to FIG. 3 but showing the load carriage in extended position;

FIG. 6 is a view similar to FIGS. 3 and 4 but showing the load carriage in a retracted position; and

FIG. 7 is an exploded view illustrating parts of my control system.

Referring to the drawings and more particularly to FIGS. 1 and 2, it will be seen that I have chosen to illustrate the construction and operation of my present novel concept as applied to a leverage system such as that which is taught in my co-pending application Serial No. 675,167, filed July 30, 1957, now Patent No. 3,024,927, issued March 13, 1962, wherein a load carriage 10, illustrated as a pair of forks 11 is shown supported for lifting movement by a primary leverage system 12 and a secondary leverage system 13.

The primary leverage system comprises a pair of vertically spaced, longitudinally extending arms 14 and 15 pivotally supporting a vertically extending arm 16 at their forward ends and each in turn pivotally supported by a pair of upstanding arms 17 at their rear ends. The forward arm 16 is connected to a transverse plate 19 from which the load carriage may be conveniently supported.

It will be seen from the description thus far that the arms 17 serve to support the arms 14, 15, and 16, as well as load carriage l0, and that the arrangement of these arms is such that they constitute a parallelogram leverage system.

In order to impart swinging movement to the load carriage, the arms 17 extend downwardly beyond their points of juncture with the arm 15. At their extended ends, the arms 17 pivotally support a ram 20, the piston of which is suitably connected to the arm 14 intermediate its ends.

The side of the parallelogram leverage system that supports the load carriage l0 and that comprises the arms 17, is itself a part of a further secondary parallelogram leverage system 13 comprising longitudinally extending parallel arms 21 and 22 that are pivotally connected to the arms 17 and extend forwardly so that their foremost ends are pivotally connected to a pair of upstanding beams 24 that may constitute an integral part of the truck frame.

In order to impart swinging motion to the upstanding amass? 3 arms 16 relatively to the beams 24, a pair of hydraulic rams is pivotally mounted at their lower ends on the truck frame and have the free ends of their pistons connected to the upper ends of the arms 17.

The concept defined thus far is presented here solely for the purpose of illustrating the utilization of my present contribution and constitutes no part of the present invention, it being exemplified in detail in my co-pending application identified heretofore.

Referring now to FIG. 3, it will be seen that to actuate the rams 2t) and 25, a fluid pump 26 is provided to pump hydraulic fluid from a sump or reservoir 27 to the rams through a conduit 29, and the fluid may be returned to the reservoir through a second conduit 38. A valve 31 is operable by a manual control lever 32 to control the flow of fluid to and from the rams.

In accordance with my present novel concept, I employ valve means 34 fordetermining the relative flow of fluid to and from the rams. Since, for the purpose of utilizing my present contribution, it is essential that the valve means 34 respond to relative movement of the respective parallelogram leverage systems, I have chosen to mount this valve on the arm 22 for movement therewith.

The valve means 34 has a body 35 formed with a longitudinal bore 36 therethrough having a pair of enlarged portions 37 and 39 adjacent the respective ends thereof. The conduits 29 and 30 are connected through suitable ports to the enlarged portions 37 and 39, respectively, of the bore 36. A conduit 40 communicates with the bore 36 between the enlarged portion 39 and the adjacent end of the valve body, and a further conduit 41 communicates with the bore 36 between the enlarged portions 37 and 39. These conduits 4t and 41 are connected at their other ends to the cylinders of the ram 20 and the rams 25, respectively. At this point, it should be made clear that, since the rams 25 always act together, their cylinders may be conveniently interconnected by a conduit (not shown). Thus, for the purpose of this description, these rams 25 will be treated as a single ram.

An elongate valve member 42 is slidable longitudinally in the bore or chamber 36 and has a diameter somewhat less than that of the bore. However, this valve member also has a pair of integral collars 44 and 45 coinciding with enlarged bore portions 37 and 39, respectively, and of substantially the same diameter as the main part of the bore 36. The valve member 42 also has a longitudinal bore 46, closed at its ends but communicating with the bore 36 through radial ports 47 and 49 disposed between the collars 44 and 45 and the adjacent ends of the valve member, respectively.

As I have stated heretofore, I provide control means for controlling the valve means so as to determine the flow of fiuid to each of the rams. These control means may comprise a reversing bell crank 50 centrally pivoted as at 51 to the arm 22 and having one end pivoted to a neck 52 integral with the valve member 42. The other end of the bell crank 50 is pivoted to one end of a link 54 that is disposed parallel to the arm 22 and has its other end pivoted to a multiplying lever 55 guided in a slide 56 formed on the arm 22.

From the description thus far, it will be seen that movement of the multiplying lever 55 to push or pull the link 54 will rock the bell crank 50 about its center 51 to move the valve member 42 in a direction opposite to the direction of movement of the link 54.

In order to actuate the valve control means that I have just described, I provide means that automatically respond to relative movement of the lifting rams 20 and 25 to maintain coordinated movement of the primary and secondary leverage systems. These means comprise a link 57 that has one end pivoted at 59 to the arm 15 of the primary leverage system at a point adjacent the upstanding arms 17. The opposed end of this link 57 is pivoted at 60 to one end of a bell crank 61, the opposite end of which is, in turn, pivoted to an end of the multiplying lever 55. The bell crank 61 is supported on a pivot 62 carried by an elongate rod 64 and normally concentric with the pivot that connects the arms 17 and 22. The rod 64 is normally parallel to the arm 22 and has one end disposed over the pivot connecting the arms 22 and the beams 24, while the end of the rod that carries the pivot 62 is formed with a finger 65 that extends beneath a bracket 66 on the arm 22 for sliding engagement therewith.

In operation, to actuate the rams 20 and 25 in order to effect coordinated movement of the leverage systems, the control lever 32 is moved in the direction of the arrow marked HOIST whereby the valve 31 enables the pump 26 to pump fluid from the reservoir 27 through the conduit 29 to the bore or chamber 36 of the valve means 34. From the chamber, fluid flows through the conduits 4t and 41 to the rams 20 and 25 to protract them, thereby raising the arms 17 about the beams 24 and the carriage 18 about the arms 17. If the rams 20 and 25 are designed to operate at equal pressures, the valve means 34 will, of course, permit equal flow to the rams. Thus, the leverage systems 12 and 13 will move in coordinated relation.

If, for any reason, one of the rams begins to lead or log, relatively to the other, the relative speed of movement of the arms 15 and 22 will change whereupon the link 57 will rock the bell crank 61 about the pivot 62 causing the multiplying lever 55 to pivot in the slide 56. This movement is transferred through the link 54 and the reversing bell crank 50 to the valve member 42 to correct the relationship of movement of the rams. For example, if we assume that while hoisting, the ram 25 begins to lead the ram 20, it will be seen that the arms 21 and 22, will move faster, relatively to the beams 24, than the arms 14 and 15 will move relatively to the arms 17. The rod 57, sensing this relative difference will tend to shorten and will actually rock the bell crank 61 in a counterclockwise direction about the pivot 62. This movement will be transferred through the multiplying lever 55 to pull the link 54 thereby exerting a push on the valve member 42. As the valve member moves to the right, as viewed, the collar 44 will move towards the central portion of the bore 36 to restrict communication between conduits 29 and 41 and the collar 45 will move towards the right-hand end of the bore. Fluid under pressure will nevertheless pass freely through the port 47, the bore 46 and the port 49 to the conduit 40, and on to the ram 20. As coordinated movement of the rams is reestablished, the valve member will return to normal position.

Should the ram 20 begin to lead the ram 25, the valve member 42 will be moved to the left, as viewed, restricting flow to the ram 20 until coordinated movement is reestablished.

It will be understood by those persons skilled in the art, that during lowering of the carriage, should the ram 25 begin to lead the ram 20, the bell crank 61 will be rocked in a clockwise direction, as viewed, causing the valve member to be moved to the left, as viewed, restricting flow from ram 20 through the conduit 41 to the return conduit 30. Under this condition, fluid may pass freely from conduit 40 to return conduit 30. When the coordinated relationship is re-established, the valve memher will return to its normal position. Conversely, should the ram 20 begin to lead the ram 25 during lowering of the carriage, the relative difference in movement will be sensed by the rod 57 that will rock the bell crank 61 in a counterclockwise direction, as viewed, to move the valve member to the right, causing restriction of flow from conduit 40 to return conduit 30, while permitting free flow from conduit 41 to conduit 30. Again, the valve member will return to its normal position when the coordinated, movement of parts is re-established.

It will be recalled that as an important part of my contribution, the load may be moved in either of opposed directions as determined by manual control means that.

over-ride or supersede the automatic control means to determine the flow of fluid relatively to each of the rams. By this means, it is possible to extend or retract the carriage relatively to the main frame of the truck. To this end, I provide a control arm 67 in the form of a bell crank, one end of which may be manually engaged for rocking movement about a pivot ea conveniently supported on the truck at the operators station. The opposed end of the control arm is pivoted to one end of a link 70. The opposite end of this link 70 is, in turn, pivoted to one arm of a further bell crank 71 that is itself pivoted at 72 on the truck frame. The other arm of this bell crank is pivoted at 74 to the end of the rod 64 that is normally disposed over the pivot connecting the arms 22 and the beams 24.

To over-ride the automatic control of the valve means 34, the manual control arm 67 is rocked in either direction about its pivot 69. Such movement will rock the bell crank 71 about its pivot 72 through the link 71}. This movement will, in turn, position the pivot 74 some distance to either side of its normal position, thereby moving the pivot 62 at the other end of the rod 64 out of its normal position. Thus, the entire geometry of the valve actuating system is upset relatively to the leverage systems and the relative movement of the rams is changed from its normal coordinated condition, so that either of the rams can be made to lead the other. It is important to realize that this manual control enables the carriage to be extended or retracted during raising and lowering.

By way of example, if the operator moves the manual control arm 67 towards position 1, the link 79 will rock the bell crank 71 in a clockwise direction, as viewed, about its pivot 72 thereby moving the pivot 74 clockwise. This movement will be transferred through the rod 64 to the pivot 62 causing a similar shift of the pivot 62 to the right of its normal position. This will, in turn, cause the multiplying lever 55 to elfect a pull on the link 54 rocking the bell crank 56} to push the valve member 42. As explained heretofore, under these conditions, fluid will move from conduit 29 into the chamber or bore 36 but the collars 44 and 45, having been shifted towards the right, as viewed, will cause the fluid to flow through port 47, bore 46, port 49, conduit 44) and to ram 20, while restricting the flow to conduit 41 and ram 25. Thus, it will be seen that as the ram 2t leads the ram 25 during elevation so that the carriage describes an are relatively to the arms 17, while the arms 17 describe an are about beams 24 but under a lagging condition, the carriage will be extended. For maximum extension, as shown in FIG. 5, the manual control arm is moved all the way to position 1 shutting off flow to ram 25 entirely. During lowering, the carriage will be retracted under the conditions stated.

On the other hand, it will be understood by those skilled in the art that by moving the manual control arm towards position 2, ram 25 can be made to lead ram 26 so that the carriage may be retracted during elevation and extended during lowering. Again, by cutting off flow to ram 26 altogether, the ram 25 may effect maximum retraction during elevation, as shown in FIG. 6.

From the foregoing description, it will be seen that I have contributed a simple and effective construction that makes possible the coordinated actuation of a plurality of lifting rams, and that I have also provided means for upsetting the condition effecting coordinated actuation of the rams to allow one ram to lead or lag the other, whenever I so desire. It will also be seen that by the utilization of my novel concept for the control of a lever operated truck, for example, I enable the operator to have complete control of the load with maximum flexibility.

I believe that the construction and operation of my novel hydraulic control will now be understood, and that the advantages of my invention will be fully appreciated by those persons skdled in the art.

I now claim:

1. In a truck of the class described, a load carriage, primary and secondary lifting lever means supporting said load carriage, said primary lifting lever means being pivoted on the secondary lever means and said secondary means in turn being pivoted on the truck, said primary and secondary means effective when rotating in a normal coordinated relation to each other to lift the load carriage in a predetermined path, a pair of hydraulic lifting rams connected one for rotating each primary and secondary lifting lever means, a proportioning valve mounted on one of said primary and secondary lever means and through which fluid pressure is applied to both rams for moving said rams, a crank member pivoted relatively to said one lever means on which the valve is mounted, means connecting said crank member to the valve for actuating said valve whereby to change the proportion of fluid flowing to each ram, a link pivoted at its opposed ends to said crank member and to the other of said lever means, and the pivot points of said link being so offset relatively to the pivots of the primary and secondary lever means that the link Will rotate the crank member on its pivot when those means tend to become uncoordinated, so that the crank member by actuating the proportionin-g valve will coordinate the rotation of the primary and secondary lever means for maintaining theload carriage in its predetermined path.

2. In a truck of the class described, a load carriage, primary and secondary lifting lever means supporting said load carriage, said primary lifting lever means being pivoted on the secondary lever means and said secondary means in turn being pivoted on the truck, said primary and secondary means effective when rotating in a normal coordinated relation to each other to lift the load carriage in a predetermined path, a pair of hydraulic lifting rams connected one for rotating each primary and secondary lifting lever means, a valve mounted on one of said primary and secondary lever means, means applying fluid pressure through said valve to the rams for moving both rams, a valve member movable in said valve for proportioning between the rams the fluid flowing to said rams, a rotatable member pivoted relatively to said one lever means on which the valve is mounted and connected to the valve member of said valve, a link pivoted at its opposed ends to said rotatable member and to the other of said lever means, the pivot points of said link being so offset relatively to the pivots of the primary and secondary lever means that the link will rotate the rotatable member on its pivot when those means tend to become uncoordinated, and said rotatable member by its rotation moving the valve member so that said rams coordinate the rotation of the primary and secondary lever means, whereby to maintain the load carriage in its predetermined path.

3. In a truck of the class described, a load carriage, primary and secondary lifting lever means supporting said load carriage, including pivots through which said primary and secondary lifting lever means are connected to each other, and further pivots through which said secondary means are mounted to rotate on the truck, said primary and secondary means adapted to rotate in a normal coordinated relation to each other and to the truck to lift the load carriage in a predetermined path, a pair of hydraulic lifting rams connected one for rotating each primary and secondary lifting lever means, a valve mounted on one of said primary and secondary lever means, means applying fluid pressure through said valve to the rams for moving both rams, a valve member movable in said valve for proportioning between the rams the fluid flowing to said rams, a crank member pivoted relatively to said one lever means on which the valve is mounted and connected to the valve member of said valve, a link pivoted at its opposed ends to said crank member and to the other of said lever means, the pivot points of said link being oifset in opposed directions relatively to the pivots through which the primary and secondary lever means are connected so that the link will rotate the crank member on its pivot when those means tend to become uncoordinated, and said crank member by its rotation moving the valve member so that said rams coordinate the rotation of the primary and secondary lever means, whereby to maintain the load carriage in its predetermined path.

4. In a truck of the class described, a load carriage, primary and secondary lifting lever means supporting said load carriage, said primary lifting lever means being pivoted on the secondary lever means and said secondary means in turn being pivoted on the truck, said primary and secondary means effective when rotating in a normal coordinated relation to each other to lift the loadcarriage in a predetermined path, a pair of hydraulic lifting rams connected one for rotating each primary and secondary lifting lever means, a proportioning valve mounted on one of said primary and secondary lever means and through which fluid pressure is applied proportionally to each ram for moving both rams, a crank member pivoted relatively to said one lever means on which the valve is mounted, a link pivoted at its opposed ends to said crank member and to the other of said lever means, the pivot points of said link being so ofiset relatively to the pivots of the primary and secondary lever means that the link will rotate the crank member on its pivot when those means tend to become uncoordinated, and a multiplying lever connected to the crank member and to the proportioning valve so that said member when rotated a relatively small degree will effectively actuate said valve to change the proportion of the fluid applied to each ram, whereby to coordinate the rotation of the primary and secondary lever means for maintaining the load carriage in its predetermined path.

5. In a truck of the class described, a load carriage, primary and secondary lifting lever means supporting said load carriage, said primary lifting lever means being pivoted on the secondary lever means and said secondary means in turn being pivoted on the truck, said primary and secondary means eife'ctive when rotating in a normal coordinated relation to -each other to lift the load carriage in a predetermined path, a pair of hydraulic lifting rams connected one for rotating each primary and secondary lifting lever means, aproportioning valve mounted on one of said primary and secondary lever means and through which fluid pressure is applied proportionally to each ram for moving both rams, a crank member connected to the proportioning valve, a pivot mounting the crank member for rotation on said one lever means on which the valve is mounted, a link pivoted at its opposed ends to said crank member and to the other of said lever means, the pivot points of said link being so offset relatively to the pivots of the primary and secondary lever means that the link will rotate the crank member on its pivot when those means tend to ecome uncoordinated, said crank member then actuating the proportioning valve .to change the proportion of fluid flowing to each ram so as to coordinate the rotation of the primary and secondary lever means, and means for shifting the pivot on which the crank member rotates, so that said link, crank member and valve will coordinate the lever means to lift the load carriage in one predetermined path or another.

References Cited in the file of this patent UNITED STATES PATENTS 521,256 Browne June 12, 1894 955,852 Coyle Apr. 26, 1910 2,350,795 Monier -4; June 6, 1944 2,613,822 Stanley Oct. 14, 1952 2,674,500 Hukari Apr. 6, 1954 2,731,162 Walstrom Ian. 17, 1956 2,793,772 Vig May 28, 1957 2,883,077 Pilch -5 Apr. 21, 1959 FOREIGN PATENTS 1,061,178 France Nov. 25, 1953 

